Door latches

ABSTRACT

A TUBULAR MORTICE LATCH HAS A ROTARY ACTUATING MEMBER FOR COUPLING TO A DOOR HANDLE AND AN INTERMEDIATE FOLLOWER MEMBER. BOTH MEMBERS PIVOT WITHIN A HOUSING ABOUT PARALLEL AXES, AND THE ACTUATING MEMBER ENGAGES AND TURNS THE FOLLOWER MEMBER WHICH IN TURN ENGAGES A BOLT TO WITHDRAW THE LATTER INTO THE HOUSING. THERE IS A PEG AND SLOT CONNECTION BETWEEN THE MEMBERS, AND THE SLOTTED MEMBER IS MOULDED FROM A RESILIENT MATERIAL WITH THE SLOT HAVING A REDUCED MOUTH SO THAT DURING ASSEMBLY IT SNAPS ON TO THE PEG.

M. J, JAMES DOOR LATCHES Se t. 29,1971 1 I Sheets-Shoot 1 Filed May 201969 39 l all/7,954

% ATTORNEYS United States Patent 3,606,425 DOOR LATCHES Michael JosephJames, Charlton Kings, Cheltenham, England, assignor to Micro &Precision Mouldings (Cheltenham) Limited, Cheltenharn, England Filed May20, 1969, Ser. No. 826,185 Claims priority, application Great Britain,May 27, 1968, 25,325/68 The portion of the term of the patent subsequentto Mar. 3, 1987, has been disclaimed Int. Cl. E05c 1/16 US. Cl. 292-1735 Claims ABSTRACT OF THE DISCLOSURE A tubular mortice latch has a rotaryactuating member for coupling to a door handle and an intermediatefollower member. Both members pivot within a housing about parallelaxes, and the actuating member engages and turns the follower memberwhich in turn engages a bolt to withdraw the latter into the housing.There is a peg and slot connection between the members, and the slottedmember is moulded from a resilient material with the slot having areduced mouth so that during assembly it snaps on to the peg.

This invention relates to door latches of the mortice type having aslidable slam bolt mounted in a housing of generally tubular form, inuse the latch being released by withdrawal of the bolt into the housingby turning door handles respectively mounted on opposite sides of thedoor and interconnected by an operating shaft. A door latch of this typeis hereinafter referred to as a tubular mortice latch and the inventionis an improvement in or modification of the invention disclosed in thespecification of my co-pending application for Letters Patent No.622,750 now Pat. No. 3,498,660.

In the specification of said application No. 622,750 I have disclosed atubular mortice latch having a rotary actuating member for coupling to adoor handle and an intermediate follower member which pivots Within thehousing about an axis parallel to the rotary axis of the rotaryactuating member. The follower member is engaged and turned by theactuating member to release the latch, the follower member in turnengaging the bolt to produce axial withdrawal of the latter into thehousing, and the arrangement is such that the angular movement of thefollower member is greater than that of the actuating member. In thatspecification we have described a construction in which the actuatingmember has a peg and slot connection with the follower member, a peglikesection of the actuating member parallel to the rotary axis of thatmember being able to turn Within a slot in the follower member duringrelative articulation of these members during latch operation.

According to the present invention the interconnection of the actuatingand follower members is again achieved by means of a peg-like section onone engaging a slot in the other, but the slotted member is moulded froma resilient material and the slot has a reduced mouth so that duringassembly it snaps on to the peg-like section and is thereby positivelyretained in the assembled latch. This avoids any possibility of the twomembers becoming detached during latch operation, and the peg-likesection is desirably moulded on the actuating member.

The follower member preferably engages and pivots on a fixed abutment inthe housing, this engagement defining an effective pivot axis offsetvertically with respect to the bolt axis. The follower member isdesirably double-acting so that either direction of handle moveice mentwill effect latch release, and to this end the abutment may have agenerally rectangular recess with radiused corners disposedsymmetrically above and below the above axis and in either of which thefollower memher, which is received within the recess, can engage andpivot dependent on the direction in which it is turned by the actuatingmember. Two such abutment recesses may be disposed one on either side ofthe housing and within which are received projecting side limbs of thefollower member. The side limbs may respectively engage in theserecesses to define the resting position of the bolt, the follower memberbeing returned to the resting position by the bolt under the influenceof the usual latch spring.

To accommodate the relative movement of the actuating and followermembers within the housing when the said abutment recesses are employed,the peg and slot connection is preferably such that the peg can slidefreely by an appropriate amount within the slot in a direction alignedwith the longitudinal axis of the housing, considering the parts in saidresting position. The peg may extend across substantially the full widthof the follower member for engagement with aligned slots formed ininward projections of both side limbs of the follower memher, and thepeg may be moulded to extend between two web-like projecting side armson the actuating member, this construction providing relative laterallocation for the two members. In a preferred construction each slottedprojection of the follower member fits closely between one of said sidearms of the actuating member and a central and similarly web-like armthereon, so that the actuating member is of integral mouldedconstruction with the connecting peg provided by two aligned peg-likesections each of which is of short length and rigidly supported betweentwo projecting arms of the actuating member.

All the parts of the latch, with the exception of such spring or springsas are included, may advantageously be moulded from synthetic plasticmaterial. Different materials may be used for the housing and the boltto improve the frictional characteristics; for example, an advantageousconstruction results if the bolt is moulded from a material commonlyknown by the trademark Delrin, with the housing and remaining partsmoulded in nylon. Delrin sliding on nylon provides extremelysatisfactory friction characteristics.

The invention will now be further described with reference to theaccompanying drawings which illustrate, by way of example, a tubularmortice latch in accordance with the invention. In the drawings:

FIG. 1 is an outer end view of the latch,

FIG. 2 is an axial cross-sectional view 11-11 in FIG. 1,

FIG. 3 is an axial cross-sectional view IIIIII in FIG. 2,

FIG. 4 is a lateral cross-sectional view IVIV in FIG. 2,

FIG. 5 is a lateral cross-sectional view V-V in FIG. 3, and

FIG. 6 is a scrap sectional view on the line VIVI in FIG. 3, showing thelatch in the released condition.

A moulded nylon tubular housing 1 comprises a main portion 2 formed atthe outer end with a fixing flange 3 and a guide bore 4 from which aslidably mounted slam bolt 5 projects. A closed-ended inner end portion6 of the housing 1 fits closely into the inner end of the main portion 2and is retained therein by opposed side projectons 7 which on assemblyclick into locating recesses 8 in the side wall of the main portion 2.

The portion 2 is of truncated circular cross-section, as shown clearlyin FIG. 5, having parallel side walls 9 on the line on the line on theline on the line which are disposed vertically when fitted and arejoined by arcuate upper and lower walls 10. Longitudinal strengtheningwebs 12 moulded externally on the side walls 9 lie within the overallpitch circle of the arcuate walls 10. Thus the housing 1 fits snuglyinto a plain cylindrical bore drilled from the edge of a door.

The housing portion 2 is moulded with intern-a1 side abutments 13 whichare joined by a central domed spring abutment 14 so as to leaveclearance with respect to the arcuate housing Walls 10, see particularlyFIGS. 3 and 5. The bolt is moulded with a solid outer end portion 15providing the usual bevelled and radiused nose of the bolt, and anadjoining short hollow box section 16 beyond which the bolt is split toprovide upper and lower inwardly projecting limbs 17. The limbs 17 passabove and below, and project inwardly beyond, the abutments 13. A latchreturn spring 18 is held in compression between the spring abutment 14and the solid end portion 15 of the bolt.

A moulded actuating member 19 has a square-section through aperture 20for reception of an operating shaft (not shown) which passes throughclearance holes 22 in the side walls 9 of the housing portion 2. Theactuating member 19 is journalled in the housing 1, the journals beingonly in part moulded at 23 in the main portion, thus enabling theactuating member to be fitted from the inner end of the housing. Thejournals are completed by moulded arcuate recesses at 24 in the endportion 6.

A follower member 25, which in the operative sense interconnects thebolt 5 and the actuating member 19, has an outwardly projecting centralweb 26 positioned with side clearance between the housing abutments 13.The member also has projecting side limbs 27 (FIG. 3) which engagelocating recesses 28 formed in the abutments 13. The follower web 26 hasupper and lower projecting ears 29 (FIG. 2) which enter longitudinalslots 30 in the upper and lower bolt limbs 17 and engage the inner ends32 of these slots, so that pivotal movement in either direction of thefollower member 25 within the abutment recesses 28 will result inwithdrawal of the bolt 5 into the housing 1 to release the latch. Thereleased condition With the bolt 5 fully withdrawn is shown in FIG. 6.

Each abutment recess 28 is of rectangular profile with radiused cornersdisposed respectively above and below the bolt axis, and the followerside limbs 27 have end portions of rectangular cross-section andradiused upper and lower ends 34, as shown more particularly in FIG. 6,which fit closely within the recesses 28. Thus each radiused end 34 canengage and turn in the adjacent radiused corner of the correspondingrecess 28, in which it is received in order to define a pivot axis forthe follower member 25 which axis is parallel to, and may be eitherabove or below, the rotational axis of the actuating member 19. Theresting position of the bolt 5 is defined by engagement of the sidefaces on the rectangular projecting ends of the follower side limbs 27with the bottom faces of the abutment recesses 28.

The follower side limbs 27 have inward projections 35 formed withelongated and inwardly open slots 36 aligned with the bolt axis in theresting position, as shown in FIG. 2. The actuating member 19 has threespaced outwardly projecting arms 37 joined across at the outer ends byan integral peg .38 of circular section. The peg 38 enters the slots 36in the follower side limbs 27, which limbs fit between the outwardlyprojecting arms 37 of the actuating member 19, to provide a peg and slotconnection between the actuating member and the follower member. Thuswhen the actuating member 19 is turned by means of the non-illustratedoperating shaft it turns the follower member 25 which in turn acts towithdraw the bolt, as shown in FIG. 6.

Each slot 36 is moulded with a reduced mouth, provided by inturned endlips 41, so that during assembly it snaps on to the peg-like section 38of the actuating member 19, thus utilising the natural resilience of themoulding material to retain the follower member 25 captive on theactuating member 19. There is thus no possibility of these partsbecoming detached one from the other within the assembled latch, whichis a marked advantage provided by the present invention.

As can be seen from FIG. 6, the arrangement is such that the angularmovement of the follower member 25 is considerably greater than theangular movement of the actuating member 19. The actual angular movementratio and the resultant bolt withdrawal for a given actuating membermovement depends upon the dimensions of the various parts, as will beappreciated from the foregoing description. As in the presentembodiment, it isv possible to achieve a very satisfactory bolt movementwith a maximum actuating member movement of only 20 producing an angularmovement of the follower member of about 50. This gives an idea of theadvantageous movement ratios which can be achieved by means of theinvention and without cutting away the housing wall to provide clearancefor movement of the parts. In fact, a housing is obtained without anyopen side apertures other than side apertures for the handle shaft,which is extremely advantageous as open apertures allow the entry ofwood shavings and sawdust which are almost inevitably present duringfitting.

When the latch is to be used with unsprung door furniture auxiliaryconcentric return springs 43 acting on the actuating member '19 arefitted in the end housing portion 6. The springs 43 are compressedbetween the end wall of that portion and a plunger 44- axially slidablewithin the latter. The plunger 44 has a concave recess 45 which facestowards the actuating member 19 and is engaged by an inwardly projectinglobe 46 on that member. The recess 45 and lobe 46 are so shaped thatmovement of the actuating member 19 from the resting central positionfurther compresses the auxiliary springs 43. Operative movement of theactuating member 19 is limited by engagement of one or other of theupper and lower side faces of the lobe 46 with the wall of the inner endhousing portion 6 over a region where that portion is received withinthe main portion 2,, as shown in. FIG. 6.

The plunger 44 is guided at the outer end by a. bore 47 in the endportion 6, and at the inner end by engagement of a centrally projectingstub 48 which slides in a guide bore '49 in the end portion 6. If sprungdoor furniture is used, with handle return springs of adequate strengthto return the handles and the actuating member 19, the springs 43 andthe plunger 44 can be omitted. In this case the end portion 6 merelyacts to seal the inner end of the housing 1 after the internal latchelements, other than the bolt, have been fitted through that end.

The bolt limbs .17 and the follower member 25 are formed so that theyinterengage, if the bolt 5 is pushed fully home into the housing 1, toretain the bolt in a completely retracted and non-projecting position.To this end the bolt limbs 17 are moulded with tooth-like projectionssuch as 50, see FIGS. 2 and 3, within the slots 30, and the centralfollower web 26 is moulded with corresponding recesses such as 52 forengagement by the projections 50 if the bolt is pushed fully home withthe follower (member 2 5 in the central resting position. Twoprojections 50 are respectively moulded on one side of one of the slots30 and on the opposite side of the other slot 30, the recesses 52 in thefollower member 25 being correspondingly positioned.

It is thus possible for a door manufacturer to supply doors with latchesfitted and the bolts fully retracted so that they are not liable toaccidental damage during transport and fitting of the doors. 'Inaddition a dust cap can be fitted in the open outer end of the housing,this providing a dust seal and further protecting the latch. With such adust cap in position the door can also be painted without danger of thepaint entering and gumming up the latch.

The inner end 39 of the bolt limbs 17 are considerably narrowed andextended at one side of the bolt axis, and the ends of these extensionshave radially inwardly opposing bulbous formations 40. These extensionsare received in upper and lower slots 42 in the actuating member 19which extend into the shaft receiving aperture 20, so that the bulbousends 40 (as shown in FIG. 3) enter the aperture 20 and engage the shaftresiliently when the latter is fitted. This can be utilised in a lockingarrangement employing a shaft which, in known manner, is axiallydisplaceable from one side of the door to a locking position in which itis inoperative to effect latch release. Such a shaft when in the lockingposition, in one known construction, allows the opposite side doorhandle to turn freely without turning the shaft, and the shaft may beformed with a side notch which in the locking position is engaged by theends 40'. Such engagement then acts to retain the shaft in the lockingposition until freed by inward movement of the bolt 5 when the limbextensions 39 clear the notch in the shaft.

I claim:

1. A tubular mortice latch having a housing, a bolt slidable in thehousing, a rotary actuating member for coupling to a door handle and anintermediate follower member which engages and pivots on two fixedabutments in the housing, such engagement defining an effective pivotaxis oifset vertically with respect to the bolt axis and parallel to therotary axis of the actuating member, one of said members being mouldedfrom a resilient material with an elongated slot having a reduced mouthand the other of said members having a peg-like section which engages inthe slot to provide a peg and slot connection which accommodatesrelative movement of the members and through which the follower memberis engaged and turned to release the latch, the follower member in turnengaging the bolt to produce axial withdrawal of the latter into thehousing and the arrangement being such that the angular movement of thefollower member is greater than that of the actuating member, said fixedabutments being disposed one on either side of the housing andrespectively engaged by projecting side limbs of the follower member,and during assembly of the latch the reduced mouth of the slot providinga snap-together connection between two said members.

2. A latch according to claim 1, wherein the peg is formed on theactuating member and extends across substantially the full widththereof, and said slot is one of two aligned slots which are engaged bythe peg and respectively formed in inward projections of said side limbsof the follower member.

3. A latch according to claim 2, wherein the peg extends betweenweb-like projecting side arms on the actuating member, with the sidelimbs of the follower member disposed between the side arms to providerelative lateral location of the members.

4. A latch according to claim 3, wherein each slotted projection of thefollower member fits closely between the adjacent one of said side armsof the actuating member and a central web-like arm of the actuatingmember, with the peg provided by two aligned peg-like sections each ofwhich is rigidly supported between two of the projecting arms of theactuating member.

5. A tubular mortice latch comprising a housing, a bolt slidably mountedin the housing, a rotary actuating member arranged within the housingfor coupling to a door handle, and an intermediate follower member alsoarranged within the housing so as to be engaged in turn by the actuatingmember to release the latch, one of said members being moulded from aresilient material with an elongated slot having a reduced mouth and theother of said members having a peg-like section which engages in theslot to provide a peg and slot connection which accommodates relativemovement of the members with the reduced mouth of the slot providing asnap-together connection between the two members, the follower member inturn engaging the bolt to produce axial withdrawal of the latter intothe housing within which is disposed a fixed abutment having generallyrectangular recesses with reduced corners disposed symmetrically aboveand below the bolt axis and in either of which the follower member,which is received within the recesses, can engage and pivot dependent onthe direction in which it is turned by the actuating member so that inuse either direction of handle movement will effect latch release withthe follower member turning about a pivot axis which is parallel to therotary axis of the actuating member and offset with respect to thelongitudinal axis of the bolt, the angular movement of the followermember being greater than that of the actuating member.

References Cited UNITED STATES PATENTS 506,461 10/ 1893 Beckwith292169.21 823,221 6/1906 Jorgenson 292-167X 2,160,301 5/1939 Baume292-167 2,342,477 2/1944 Magnenat 16171UX 2,701,152 2/1955 Cutler287--92 2,732,581 1/1956 Heck 16171X 3,498,660 3/1970 James 292173ALBERT G. CRAIG, JR., Primary Examiner US. Cl. X.R.

